Project Summary The long-term objective of this research proposal is to perform advanced development and analytical validation of a technology for enrichment of circulating tumor cells (CTCs). The goal is to further develop our highly efficient and specific CTC capture technology to pave the way not only for CTC enumeration to serve as a biomarker for PC to better predict clinical outcomes, but also as a source of clinical material (i.e., CTCs as a liquid biopsy) for sequential molecular analyses that can be used to direct appropriate therapies for individual patients (i.e., the right treatment for the right patient). Our joint team has demonstrated a unique, relatively inexpensive cell affinity assay, which is capable of identification, enumeration and capture of viable (preservative-free) CTCs in whole-blood samples collected from PC patients. Initially, we pioneered the concept of applying anti-EpCAM (epithelial cell adhesion molecule)-coated nanostructured surfaces as a high-affinity substrate for enrichment of CTCs. By integrating the high-affinity substrate with a microfluidic component capable of generating chaotic turbulence, further improved CTC capture efficiency (up to 99%) has recently been achieved as a result of the enhanced collisions between CTCs and the substrate. Side-by-side analytical validation was conducted to compare our nanostructure substrates with CellSearchTM assay using blood spiked with PC cell lines as well as 33 blood samples isolated from in PC patients at predefined stages. CTCs are cancer cells that break away from either the primary tumor or metastatic sites and circulate in the peripheral blood. Enumeration of CTCs has established clinical utility in patients with metastatic, castration-resistant (CR; i.e. hormone refractory) PC, in whom CTCs are an independent predictor for response to chemotherapy, disease free survival and overall survival. It is conceivable that the molecular and functional characterization of CTCs could provide much valuable information for predicting patient prognosis and monitoring therapeutic interventions and outcomes. Herein, we will first develop a new-generation integrated CTC chip capable of highly efficient and specific enrichment of CTCs with improved blood handling capacity, followed by comprehensive analytical validation using blood samples collected from PC patients at predefined stages (e.g., CRPC, PSA recurrence). We will then purify and isolate individual CTCs for quantification of 16 genes using a commercial real-time qPCR System. We propose to quantify expression of 16 genes, which we have chosen as markers of differentiation state, epithelial-mesenchymal transition, and the AR signaling axis. The molecular signatures imparted by these genes not only depict various cellular phenotypes but also offer the promise of predicting response/ resistance to anti-cancer therapeutics.